The present invention relates to pipettes which contain at least two pistons, preferably of different diameter, which move within a chamber. Plural diameter pistons in pipette chambers have been known in the past. In such pipettes, helical springs have been known to keep the pistons at an upper position, with a thumb press button, by means of which the pistons can be moved against the force of the helical springs to a predetermined lower position. When first and second springs are used, different rigidities of the springs can be used so that when the thumb button is pressed, a definite change is felt by the user after compressing the first spring, and at the point before compressing the second spring. This spring compression difference in force has been used to provide for different doses, or in some cases, to provide for an air blowout in prior art pipettes. However, the prior art has not provided a plurality of pistons movable together and separately in a pipette chamber to provide for precise small dose measurement and dispensing, along with desired air blowout to completely remove the sample, in a structure which allows movement of both pistons together in a single chamber, movement of a single piston with respect to the other in the chamber, and return of the pistons to their original starting positions.